Communication system



Nov, 13, 1945. R. c. coRDERMAN COMMUNICATION SYSTEM E TOR R. c. NODERMAN By l M @49M ATTORNEV Nov. 13, 1945. R. c. coRDERMAN COMMUNICATION SYSTEM /Nl/E/vroR R C. CORDRMAN JWM ArrQRA/Ev Patented Nov. 13, 1945 ooMMUNroATIoN SYSTEM Roy C. Corderman, Maplewood,- N. J., assignor to f Western-Electric Company, Incorporated, New

York, N. Y., a corporation of New York Application September 9, 1944, Serial No. 553,314v

l f claims. (01.25159) 'Ihis invention relates to communication systems and particularly to multiplex carrier telephone systems. Y

Objects of the invention are the stabilization of carrier frequencies used in multiplex` carrier telephone systems and particularly in systems employing ultra-high frequency .carrier currents, an elilcient assignment of channel frequencies between a central oflice and outlying stations, and the provision of circuit'arrangements which provide the desired carrier supply for the maximum number of channels without interference between channels.

The invention is a multiplex carrier telephone system comprising a plurality of oices or stations, ultra-high carrier'frequencies :being employed for transmission in both directions' between the voice'channels in one office or station and the voice channels in another office or station. Either a wireless or a wave guide transmission medium may be used. Y

' A feature of the invention is a system in which the carrier frequency produced at one terminal of a circuit between two ocesor stations 'is used as a source of stabilized frequency, for the transmission from the other terminal, by combining this frequency with an additional stabilized frequency which also originates at the first-mentioned terminal.

According to the invention two ultra-high frequency carriers are transmitted from one oflice or station of a system to another oice or station of the system, one carrier being 'transmitted without modulation and the other being modulated by the voice modulated carriers of a plurality of channels, the unmodulated carrier being combined at the other vstation With-the incoming voice modulated carrier of each channel to constitute the carrier'lsupply for transmission in the opposite direction.

The invention Will be better understood from the following description of a systemarranged in accordance with the above-mentioned features as shown inthe drawings which' form a part of this specification.' The drawings, which consist of two ligures, lshow schematically a'cen tral station and a field station ofamultiplex carrier telephone system which may include a plurality of lield stations,

The system shownY in the drawingscomprises a transmitting antenna TIA at the central station associated with a transmitter 4 for trarisy mitting signaling energy to a receiving antenna RIA and'receiver |0'I at field station |00; comprises a transmitting antennafTI-Bat the centrai station associated with the transmitter ,5*

for transmitting a stabilizer carrier to a receiving antenna RIB and receiver |05 at field station |00; and comprisesa transmitting antenna TIC at the eld station |00 for transmitting signaling energy to a receiving antenna RiCrand Vreceiver 'I at theA central station. There are a plurality of two-way voice channels I0, 20, 30 at the central station and a corresponding plural.- ity of two-way voice channels H0, |20', i30`at the iield station |00. The system is arranged so that channels I0 and I|0 are connected for communication, channels 20 and |20 are connected forl communication and channels 30and I30are connected for communication. Each other iield station has an antenna and receiver for receiv-` ing the stabilizing carrier from the central station, an antenna and receiver for receiving signal energy from the central station, and a trans- Y nels of the field station.

In the central office, the two-way voicey channels I0,v20 and 30 are individually connected to hybrid coils I|, 2| and 3| and are balanced by the balancing networks I2, 22 and 32, respectively. Voice currents from channels I0, 20 and 30 are passed through the associated hybrid coils andthrough low-pass filters I4, 24 and 34, respectively, to modulators I6, 20 and 36, respectively. Each of the modulators is provided with a carrier source of a different frequency, the carrier current source |'I of modulator I0 being of a frequency AI, the carrier current source 2l of modulator 20 being of a frequency A2, and the carrier current source 3l of modulator'30 being of a frequency A3. VThe output ofeach of modulators I6, 26 and 36 and thel modulators of other channels previdedr for communication with field station |00 is connected by conductors vI to a group modulator 2. The carrier source 3 associated with modulator 2` is of 'an Vultra-high frequency Y, and the carrier current from this source is modulated bythe output of each of modulators I6, 26 and 36.4 The output of modulator 2 isfapplied through an amplier to the inputl side of the transmitter 4 associated with the directional antenna TIA; and this antenna is aimed at the vantei'tinaRIA at iield station |00l so that signal energy from each of the voice channels associated with `group modulator 2 is transmitted to field station I 00.

Another-group of itwo-waywoice channels is transmitting a stabilizing .carrier to said second station, means in said second station for receiving said stabilizing carrer and for individually mixing said carrier with incomng signal energy passed by each of the channel lters in'said second station to constitute a carrier source of a dil'erent frequency for each of the modulators in said second station, andmeans common to the modulators of said second station for transmitting the signal energy from said modulators to said rst station. l

'2. In a telephone system, a rst station, a second station, voice channels in said, stations, there being a Voice channel in each station for communication individually with a particular one of the channels in the other station, a modulator and a channel lter individual to each of said voice channels, a carrier sourcev of a different frequency for each of the modulators in said irst station, means including an ultra-high frequency carrier current source common to the modulators in said rst station for transmitting signal energy Vfrom said modulators to said second station,

means including the channel iilters in said second station for receiving and selectively transmitting the signal energy incoming from said first station to the corresponding voiceV channels in said second station, means includingY a second ultra-high frequency carrier source in said rst station for transmitting a stabilizing carrier to said second station,--means in said second station for receiving saidstabilizing carrier and for individually mixing said carrier with incoming signal energy passed by each of the channel lters in-said second station Vvto constitute a carrier source f a dierent frequency foreach ofthe modulators in said second station, means common to the modulators of said second station for transmitting the signal energy from said modulaters to said rst station, and means including the channel lters of said first station for receiving and selectively transmitting the signal energy incoming from said second station to the corresponding voice channels in said first station.

3. In a telephone system comprising a central station and a iield station, a plurality of voice channels at a field station, a corresponding plurality of voice channels at the central station, a modulator and a detector for each of said channels, channel lters, one for each of said detectors, each of said filters tuned to pass only the voice modulated carrier current of the frequency of the carrier supplied to the modulator of the corresponding voice channel at the other station, a diierent carrier current source for each modulatoi` in said central station, a modulator common to said channel modulators in said central. station, a carrier current source for said common modulator, another carrier current source at the central station, means including antennae at said stations for separately transmitting signal energy from said common modulator and energy from said other carrier current source at said central station to said iield station, means including the channel filters and detectors at said field station for selectively transmitting the incoming signal energy to the voice channels of said iield station, means for mixing the incoming carrier of each channel of the field station with said other carrier to constitute the carrier current source for the modulator of that channel, means comprising a transmitting antenna at said field station common to the modulators of all of the channels thereat and a receiving antenna at said central station common to the detectors of the channels offsaid central station which correspond tol the voice channels of said eld stationV for transmit; ting signal energy from the modulators ofsaid eld station vto said central station, and means including the channel lters and detectors of the voice channels of the central station Yfor selectively transmitting .the incoming signal energy to the voice channels-ofsaid central station.

4. In a communication system, a central station, a plurality of eld stations,y a .plurality of .voice channels ateach field station, voice channels at said central station, each Voice channel of said central station corresponding to a different o'ne of theV voice channels of said field stations, a modulator and a detector and a channel filter individual to each voice channel of said central station, a carrier current sourcevof va different frequency for each modulator at said .central station,A a plurality of group modulators .at said central station, each group modulator common to the modulators of voice channels of the central station corresponding to Voice channels of the same :field station, an ultra-high fre,- quency carrier current source 'for each of said group modulators, Ia transmitter and transmitting antenna for each of said group modulators for transmitting to a eld station signal energy from the voice channels of the central station ,corresponding to thev voice channels of the field station, a receiving antenna and receiver at each iieldstation for receiving from the corresponding transmitting antenna at the central station signal energy from the voice channels of the central station corresponding to the voice channels of the iield station, a modulator and a detector and a channel filter individual to each voice channel of said field stations, the lilters of the `channels of saidfield stations being tunedl to the frequencies of the carriers of thev corresponding channels respectively'of the central station, means comprising the detectors and associated filters at the eld stations for transmitting to each voice channel respectively the voice frequency signaling energy from the corresponding voice channel of the central station, means comprising an ultrahigh-frequency carrier source and transmitter and antenna at said central station for transmitting a stabilizing carrier to all of said field stations, an antenna and a receiver at each of y said eld stations for receiving the stabilizing carrier from said central station, means individual to each of the modulators at the field stations for combining said stabilizing carrier with incoming voice modulated carrier current transmitted through the channel filter of the associated voice channel to constitute the individual carrier source for each of the modulators of the field stations, means at each eld station comprising a transmitter and antenna common to the modulators of said field station for transmitting signal energy from all of the associated voice channels to said central station, means comprising an rantenna and a receiver at said central station individual to each of said iield stations for receiving signal energy from said field stations respectively, means comprising the channel filters of the voice channels of the central station for transmitting to the detector of each voice channel of the central station signal energy received from the corresponding voice channel of the eld stations, each of the channel filters of said central station being tuned to the frequency of the carrier supplied to the modulator of the corresponding voice channel of the field stations, and means comprising each detector at the central station for transmitting to each voice channel voice frequency signal energy from the corresponding voice channel of the eld stations.

5. In a communication system,- a central station, a plurality of eld'stations, a plurality` of voice channels at each neld station, voice channels at said central station, each voice channel of said central station corresponding to a different one of the voice channels of said field stations, a modulator anda detector anda channel lter individual to eachv voice channel of said central station, a carrier source of a'diierent frequency for each modulator at said central station, adjacentones oi' said carrier frequencies being assigned in succession to the modulators associated with different'group modulators, Va plurality of `groupmodulators at said central office, each group modulator common to the modulators of the voice channels corresponding to voice channels of the same eld station, an ultra-high-frequency carrier source for each of said group modulators, a transmitter and transmitting antenna for each of said Agroup modulators for transmitting to a eld station signal energy from the voice channels of the central station corresponding to the voice channels of the field station, a receiving antenna and receiver at each eld station for receiving from the corresponding transmitting antenna at the central station signal energy from the voice channels of the central station 'corresponding to the voice channels of the field station, a modulator and a detector and a channel iilter individual to each voice channel of said :field stations, the filters of the channels of said field stations-being vtuned to the frequencies of the carriers of the corresponding channels respectively oi? the central station, means comprising the detectors and associated each voice channel respectively the lvoice frequency signaling energy from the corresponding voice channel of the central station, means comprising an ultra-high-irequency carrier source and transmitter and-antenna at said central station for transmitting a stabilizing carrier to all of said field stations, an antenna and a receiver aty each of said eld. stations for receiving the stabilizing carrier from said central station,

means individual to each of the modulators at the channel lters of the voice channels of the central station for transmitting to the detector of each voice channel of the central station signal energy received from the corresponding Voice channel of the field stations, each of the channel lters of said central station being tuned to the frequency'of the carrier supplied to the modulator of the corresponding voice channel of the iield stations, and means comprising each detector at the central station for transmitting to from the corresponding voice channel of the field stations.

ROY C. CORDERMAN.

filters at the iield stations for transmitting to 

